Synthesis of covalently linked linear porphyrin triad and tetrad containing different porphyrin sub-units

Covalently linked diarylethyne bridged unsymmetrical porphyrin triad containing ZnN₄, N₄, and N₂S₂ porphyrin sub-units and porphyrin tetrad containing ZnN₄, N₄, N₃S, and N₂S₂ porphyrin sub-units were synthesized over sequence of Pd(0) mediated coupling reactions. The triad and tetrad are freely soluble in all common organic solvents and characterized by ES-MS, NMR, absorption, fluorescence, and electrochemical techniques. The ¹H NMR, absorption, and electrochemical studies indicated a weak interaction between the porphyrin sub-units of porphyrin triad and porphyrin tetrad. The steady state and time-resolved fluorescence studies supported an energy transfer from one end of porphyrin array to the other end. This kind of porphyrin arrays containing different porphyrin sub-units will be useful for molecular electronics applications.     

Study of the order-disorder transitions in methoxy-functionalized polyalkylthiophenes

This article describes the solvatochromic properties of two polyalkylthiophene (PAT) samples functionalized at the end of the hexamethylenic side-chains with a methoxy group, which is able to strongly enhance the solubility, workability and filmability of this kind of polymers. The latter are obtained using either a regioselective or a regiospecific polymerization procedure, thus leading to a different configurational order in the final polymer. The optical features of the synthesized samples—which are very interesting for chemosensor and electrooptical applications—are observed in many solvent/non-solvent systems and derive from the conformational modification of the conjugated backbone induced by side-chain order-disorder transitions. These transitions strongly depend on the content of HT dyads; a fact which undeniably shows the importance of the polymer configuration, directly deriving from the adopted polymerization method, on the final electrical and electronic properties of the obtained material. The low sensitivity of the regioregular sample towards the temperature changes together with its higher tendency to give thick, semicrystalline and self-consisting films makes it very promising for the obtainment of organic semiconductors for electronic devices subjected to high temperature variations.     

Y(OTf)3 catalyzed substitution dependent oxidative C(sp)–C(sp) cleavage and regioselective dehydration of β-allyl-β-hydroxydithioesters: alternate route to α,β-unsaturated ketones and functionalized dienes

β-Allyl-β-hydroxydithioesters have been generated by the regioselective Grignard addition to the β-oxodithioesters. They have been successfully employed in selective C(sp³)–C(sp³) bond cleavage to construct α,β-unsaturated ketone residues by the treatment of an emerging catalyst yttrium(III)triflate for the first time. On the other hand, hetaryl substituted β-allyl-β-hydroxydithioesters led to the useful diene precursors through selective dehydration under the similar conditions.     

Iron oxide nanoparticles supported on NH2- and COOH-functionalized SBA-15

Iron modified NH₂- or COOH- functionalized SBA-15 is characterized by XRD, N₂-physisorption, TPR-TG, FTIR, M?ssbauer spectroscopy and methanol decomposition. The material obtained from COOH-functionalized silica exhibits the highest catalytic activity.     

Construction of supported lipid membrane modified piezoelectric biosensor for sensitive assay of cholera toxin based on surface-agglutination of ganglioside-bearing liposomes

A novel piezoelelctric biosensor has been developed for cholera toxin (CT) detection based on the analyte-mediated surface-agglutination of ganglioside (GM1)-functionalized liposomes. To achieve a CT-specific agglutination at the surface, the gold electrode is modified by a GM1-functionalized supported lipid membrane via spontaneous spread of the liposomes on a self-assembled monolayer of a long-chain alkanethiol. In the presence of CT, the GM1-incorporated liposomes in assay medium will rapidly specifically agglutinate at the electrode surface through the binding of CT to GM1 on the electrode surface and the liposome interface. This results in an enormous mass loading on the piezoelelctric crystal as well as a significant increase of density and viscosity at the interface, thereby generating a decrease in frequency of the piezoelelctric crystal. The combination of mass loading with interfacial change in the surface-agglutination reaction allows the developed piezoelelctric biosensor to show substantial signal amplification in response to the analyte CT. The detection limit can be achieved as low as 25 ng mL⁻¹ CT. This is the first demonstration on CT detection based on specific surface-agglutination of GM1-modified liposomes. The supported lipid layer based sensing interface can be prepared readily and renewably, making the developed technique especially useful for simple, reusable and sensitive determination of proteins.     

Potentiometric detection of polyions based on functionalized magnetic nanoparticles

A novel potentiometric detection strategy based on functionalized magnetic nanoparticles has been developed for rapid and sensitive sensing of polyions. Highly dispersed magnetic nanoparticles coated with ion exchanger and plasticizer could promote an in situ cooperative ion-pairing interaction between the ion exchanger and the polyion analyte in sample solution by dramatically reducing the mass-transfer distance. With applying a magnetic field, the nanoparticles can be attached to the surface of ion exchanger free polymeric membrane. The observed potential signals are related to the polyion concentrations. The proposed polymeric membrane electrode exhibits a linear relationship between the greatest potential response slope (dE/dt) and the logarithm of protamine concentration in the range of 0.05−5 μg/mL with a lower detection limit of 0.033 μg/mL.     

卟啉修饰碳纳米管研究进展

碳纳米管作为一类新型纳米材料具有许多独特的物理、化学性质,卟啉在可见光区具有广泛吸收.并可作为构筑分子体系的光捕捉单元.卟啉修饰的碳纳米管有望在生命、信息、材料科学等许多相关学科得到应用.本文综述了卟啉修饰碳纳米管的方法、影响因素,展望了其在光电领域的应用前景.     

Pore-functionalized polymer membranes for preconcentration of heavy metal ions

Functionalized membranes containing carboxylate, phosphate and sulfonate groups were prepared by UV-initiator induced graft polymerization of the functional monomer (acrylic acid, ethylene glycol methacrylate phosphate (EGMP) and 2-acrylamido-2-methyl-1-propane sulfonic acid) with a crosslinker (methylenebisacrylamide) in the pores of poly(propylene) host membranes. The functionalized membranes thus obtained were characterized by gravimetry, FTIR spectroscopy, radiotracers and scanning electron microscopy for the degree of grafting and water uptake, presence of functional groups, ion-exchange capacity, and physical structure of the membranes, respectively. The uptakes of Cs⁺, Ag⁺, Sr²⁺, Cd²⁺, Hg²⁺, Zn²⁺, Eu³⁺, Am³⁺, Hf⁴⁺ and Pu⁴⁺ ions in the functionalized membranes were studied as a function of acidity of the equilibrating aqueous solution. Among the functionalized membranes prepared in the present work, the EGMP-grafted membrane (with phosphate groups) showed acid concentration dependent selectivity towards multivalent metal ions like Eu³⁺, Am³⁺, Hf⁴⁺ and Pu⁴⁺. The solvent extraction studies of EGMP monomer in methyl isobutyl ketone (MIBK) solvent indicated that divalent and trivalent metal ions form complexes with EGMP in 1:2 proportion, but the distribution coefficients of trivalent metal ions were significantly higher that for the divalent ions. The uptakes of Eu³⁺ ions in monomeric EGMP (dissolved in MIBK) and polymeric EGMP (in the forms of crosslinked gel and membrane) were studied as a function of concentration of H⁺ ions in the equilibrating solution. This study indicated that polymeric EGMP has better binding ability towards Eu³⁺ as compared to monomeric EGMP. The variation of distribution coefficients of Eu³⁺/Am³⁺ in gel and membrane as a function of H⁺ ion concentration in the equilibrating aqueous solution indicated that ionic species held in the membrane and gel were not same. These results indicated that proximity of functional groups (phosphate) plays an important role in metal ion binding with polymeric EGMP.     

Analysis of fungal cyclopentenone derivatives from Hygrophorus spp. by liquid chromatography/electrospray-tandem mass spectrometry

Fruitbodies of the genus Hygrophorus (Basidiomycetes) contain a series of anti-biologically active compounds. These substances named hygrophorones possess a cyclopentenone skeleton. LC/ESI-MS/MS presents a valuable tool for the identification of such compounds. The mass spectral behaviour of typical selected members of this group under positive and negative ion electrospray conditions is discussed. Using the ESI collision-induced dissociation (CID) mass spectra of the [M + H]+ and [M - H]- ions, respectively, the compounds can be classified with respect to the substitution pattern at the cyclopentenone ring and the type of oxygenation at C-6 (hydroxy/acetoxy or oxo function) of the side chain. The elemental composition of the fragment ions was determined by ESI-QqTOF measurements. Thus, in case of the negative ion CID mass spectra an unusual loss of CO2 from the deprotonated molecular ions could be observed.     

Enhanced Sensing of Carbendazim,a Fungicide on Functionalized Multiwalled Carbon Nanotube Modified Glassy Carbon Electrode and Its Determination in Real Samples

An electrochemical sensor was developed by modifying a glassy carbon electrode (GCE) with functionalized multiwalled carbon nanotubes (FMWCNTs). The fabricated electrode was used to examine the redox behavior of carbendazim (CAR) in different pH solutions (pH 1.0–13.0). Surface morphology of the modified film was studied by scanning electron microscopy (SEM). An electroanalytical procedure for the determination of CAR was developed by adsorptive differential pulse stripping voltammetry (DPSV) over the range 0.01–5 × 10⁴ µ g L^?1. The developed procedure was also validated in real samples such as soil and water samples, and the applicability of the reported method is highly encouraging.